The present invention relates to electrical switching devices and particularly to switching devices having a sliding wiper contact for movement along a plurality of spaced stationary contact strips. Such slide type switching mechanism are known to be employed in electrical programmers for controlling the duty cycle functions of automotive air conditioning and temperature control systems.
In providing electrical programmers for automotive temperature control systems, it is known to provide a fluid pressure operated actuator for moving a slider block for an electrical switching mechanism. Typically, such a device employs a vacuum motor having an actuator rod or wire extending from the motor diaphragm and interconnected with the movable slider of the electrical programming switch. The movable slider has a conductive wiper thereon for bridging stationary discrete contacts on the housing of the switching mechanism for providing the desired switching functions as the movable slider is moved in response to movement of the vacuum motor actuator.
In designing slide type switching mechanism suitable for automotive temperature control system programmers, it has been required to provide a plurality of individual stationary contact strips attached to the switch housing for making contact with the wipers provided on the switch slider. This known construction technique has required the forming, placing and positioning of individual thin metal contact strips into the switch housing and providing means for retaining each of the individual contact strips therein. Heretofore, upon placement and positioning of the individual contact strip, it has been necessary to provide tabs received through apertures in the housing for bending of the tab after placement of the strip onto the housing to retain the strip thereon. Alternatively, the individual contact strips may be retained on the switch housing by one or more rivets received through apertures in the strip and housing.
The aforesaid switch construction employing individual stationary contact strips, for traverse by a sliding wiper contact, has resulted in difficult assembly operations in mass production in the placement and retaining of each of the individual stationary contact strips. Furthermore, the requirement of individually placing and retaining the contact strips on the switch housing has resulted in successive hand assembly operations which inherently yield high manufacturing costs in mass production.
There has thus existed a long felt need to provide an electrical switching mechanism of the sliding wiper type and for providing such a switching mechanism which was capable of high speed easily assembled low cost fabrication in volume production. In particular, there has been a need for a way or means of providing such a switching mechanism of the type having a plurality stationary individual contact strips mounted on the switch housing for making contact with a sliding wiper.